Medical Package Printing: Thermal-Transfer Systems Challenge Flexographic Printers
The need to include more variable information on medical packages is driving some device packagers to consider thermal-transfer printing. Can flexography survive?
by Daphne Allen, Editor
Flexographic printing is by far the most widely used printing method for flexible medical packaging. But thermal-transfer printing may soon start chipping away at its market share. As more and more device companies become global marketers, the number of languages and internationally understood symbols that need to be printed on packages increases. And, to comply with European market regulations, packages must bear lot codes and expiration dates. Suddenly, the use of flexographic printing plates that need to be updated from run to run is not so economical.
To cope with these demands, a few medical device companies have turned to thermal-transfer printing. Easily programmable, thermal-transfer systems are not bound by the limits of a printing plate and can instead output variable information directly from a database.
Constant data on packages from Kendall Healthcare, formerly Graphic Controls, is printed in purple by a flexographic printer. A thermal-transfer printer produces the variable data in black.
Not all flexographic printer makers and users are abandoning the several-hundred-year-old technology, though. New inks and plate materials still make flexography an appealing option, and smaller systems help device makers afford the technology for smaller volumes. Converters still use the technology widely, because they are often employed by their clients to print constant information and provide preprinted packaging materials. So, instead of one technology dominating the other, what may emerge in the in-house medical printing market is a partnership between flexography and thermal-transfer printing.
PITTING FLEXOGRAPHY AGAINST THERMAL TRANSFER
According to the Flexographic Technical Association (Ronkonkoma, NY), 70% of the films in the $18-billion flexible film industry are printed on using flexography. "It is the most common method when it comes to medical printing," says Carl Marotta, president of Tolas Health Care Packaging (Feasterville, PA), a converter of medical packaging films, the bulk of whose printing is done using flexography. "It is versatile and inexpensive to operate." Another converter, Perfecseal (Philadelphia), uses flexography exclusively. "It is more suitable than thermal-transfer printing for printing on foil, films, and Tyvek brand spunbonded olefin," says Perfecseal's printing operations manager Ron Fortunato.
Wazir Nobbee, senior research engineer at DuPont Tyvek (Richmond, VA), adds that the technology produces good print quality at high speeds—often hundreds of feet per minute. "It is very economical for large volumes. You can print a whole roll of material without stopping, whereas other methods are stop and go." Nobbee's colleague at DuPont, Stasys Rudys, even finds flexography to be more efficient than thermal-transfer printing. "You can print on much wider webs and at much faster speeds. And it is better for producing fine lines and logos."
As fast, economical, and capable as it is, flexography cannot compare to thermal-transfer printing when it comes to changing the content of the printed text. When text or codes need updating during flexographic printing, users must change printing plates—sometimes even make new ones, which can cost up to $500 each. But when operators want to change text or expiration dates using a thermal-transfer system, all they need to do is make a keystroke change and send it to the printer. "When you are required to change plates frequently, it becomes justifiable to make the switch," says Tom Pugh, vice president of sales and marketing at Bell-Mark (Pine Brook, NJ).
Device packagers are faced with such frequent printing changes now more than ever because of the market demand for bar codes, lot numbers, and expiration dates. There is also the need to print in multiple languages. Medtronic DLP (Grand Rapids, MI), for instance, was spending $150,000 to $200,000 per year on plates for printing multiple languages on its cardiovascular device packaging.
Another reason device manufacturers may not really benefit from using flexographic systems is that high-speed printing may not be a priority, especially when many in-house packaging departments use form-fill-seal systems, says Rudys. "Form-fill-seal machines are normally intermittent, so achieving continuous high speeds is no longer the issue." And thermal-transfer printers do not move at a snail's pace, either. Pugh says that Bell-Mark's EasyPrint thermal-transfer system uses a near-edge printhead that prints at an angle, rather than perpendicularly, allowing the system to move at high speeds on all substrates.
Still, some feel thermal-transfer printing is too expensive. "Flexographic printing is simple and more cost-effective than thermal transfer," says one industry insider.
A NEW PARTNERSHIP
Rather than force flexographic systems out of the market, thermal-transfer printers may just end up partnering with them. Use of the two systems may allow companies to get the best of both worlds: a low-cost, easy-to-operate flexographic system for producing high-quality standard information, and an easily programmable thermal-transfer system that can handle variable information. Says Matt Malot of Multivac (Kansas City, MO), a provider of form-fill-seal systems, "Device companies often want to place both a flexographic printer and a thermal-transfer printer right on their machines." That is just what Graphic Controls Corp. (Chatsworth, CA), now known as Kendall Healthcare Products Co., did when it decided to market its sterile gloves, needle counters, and other devices in Europe.
Graphic Controls had been using a hot stamper mounted on its form-fill-seal machine to print variable information on preprinted polyethylene top webs. But the hot stamper could print only a limited amount of variable information, says Noel Gharibian, Graphic Controls's engineering manager for its Devon line of products made in Chatsworth, CA. Because the hot stamper was not programmable, Gharibian had to manually change the stamper's metal letters in order to make a print change. Use of a thermal-transfer printer from Greydon Inc. (York, PA) enabled the firm to print part numbers, product descriptions, quantities, lot codes, and use-before dates, all generated by a computer.
But to print company name and contact information, graphics and symbols, and standard information in multiple languages, the company opted for an in-line flexographic printer, also from Greydon. "It was too expensive for the firm to maintain a preprinted inventory from a converter," says Greydon's Greg Rochon. Graphic Controls's new system (of which it has installed four) consists of two traversing thermal-transfer printers mounted on top of a flexographic printer. With the flexographic printer, the firm was able to match the quality of the preprinted stock. To help the variable information stand out from the constant, the thermal- transfer system prints in black, while the flexographic system prints in purple.
But the printer partnership doesn't work for everyone. Medtronic DLP's Tom Roberts says that not only did he want a programmable printer, like the thermal-transfer system he purchased from Bell-Mark, he wanted to get rid of the ink and plates necessary for flexographic printing. "The ink is messy, and you need to replace the plates all the time, even if you aren't making a text change, because the plates wear out," Roberts says. "Plus, when you have two different printing systems, you need to have technicians trained in different technologies to do repairs and maintenance." To avoid these concerns, Roberts says he uses thermal-transfer printers to produce both variable and constant information. The printers are mounted on a Tiromat 3000 form-fill-seal machine.
FLEXOGRAPHIC STRIKES BACK
Despite such criticisms, the use of in-house flexographic systems has its benefits. Bell-Mark's Pugh says that they help firms eliminate preprinted inventory, and they handle short runs quickly—all you need to do is change the plate. Also, "printing in line with a rotary flexographic printer mounted on a form-fill-seal machine is still the most economical method of in-line printing," says Pugh. "It is most appropriate in applications where static information doesn't change frequently."
The technology behind flexography is also improving. Plates, once either molded out of rubber or laser engraved, are now available in photopolymer. These plates, for example those made of DuPont's Cyrel material, are exposed to light to create the lettering. "They are more compatible with computer-to-plate technology," says DuPont's Rudys. "Their low durometer is well suited to Tyvek, because Tyvek is not as uniform as other materials, and the plates give a little to conform to the printed medium."
To meet Environmental Protection Agency's requirements for reducing the use of volatile organic compounds, industrial printers, including flexography users, have switched from solvent-based inks to water-based inks for some applications. But device companies must ensure that a particular water-based formulation adheres to a medical packaging substrate and withstands the sterilization process and shipping. Tolas's Marotta says that companies need to understand exactly how the packaged device will be sterilized in order to find a stable ink. "For instance, you need to find a water-based ink that can withstand steam sterilization," says Marotta. He doubts the existence of a universal ink that can withstand all methods of sterilization. "Inks have a relative versatility but no one ink will satisfy every need."
Anilox rolls, the mechanisms that apply the ink to the plates, have also improved. Laser-engraved ceramic rollers are much improved over mechanically engraved rollers. According to Perfecseal's Fortunato, the laser controls the depth of cut to achieve very tight tolerances for much finer screen counts. Finer screen counts help transfer consistent amounts of ink to the printing plates. "This helps flexography compete with rotogravure printing," says Fortunato.
Another printing method may become a bigger player in the medical market. SRI International (Menlo Park, CA), a nonprofit research institute, says medical firms should watch for advances in ink-jet printing technologies for producing variable data. "Ink-jet printers can also be computer-driven, and SRI has done a lot of innovation in low-volatile inks that can survive sterilization," says Eric Shrader, program manager for SRI. Shrader says the U.S. Postal Service has recently replaced its flexographic printing system with an ink-jet system to produce high-density bar codes that take the place of date stamps on letters.
Dale Ploeger, SRI's director of innovative product engineering and technologies division, says ink jets may also solve an unspoken need. "Ink jets can print on filled packages," whereas thermal transfer needs to be done on a flat surface. Two ink-jet suppliers are currently working to develop higher-quality printing systems: Domino Amjet (Gurnee, IL) and Videojet Systems International (Wood Dale, IL).
It doesn't appear as though thermal-transfer printing will totally replace flexographic printing anytime soon. A number of affordable flexographic systems, like models from Bell-Mark, Greydon, and Kiwi Coders Corp. (Wheeling, IL), make high-quality, high-speed flexographic printing a viable option for smaller device companies. Converters also rely heavily on the larger, more expensive systems.
Instead, medical device packagers may come to rely on a combination of in-house printing systems to achieve their own priorities. Such unions have proved successful for some medical companies, so packaging engineers shouldn't hesitate to add more-efficient printers to their lines if it means successfully and economically meeting new demands for variable data.